Field of the Invention
The present invention relates to an image forming system and an image forming apparatus.
Description of the Related Arts
In commercial printing in recent years, there are many cases where a job using a plurality of sheet types is executed. Examples of such a job include creation of a booklet by combining a thick sheet into ordinary sheets. For this purpose, an image forming system is provided with multi-stage sheet supply trays and is configured to be able to place sheets with a plurality of sheet types onto separate sheet supply trays beforehand. With this configuration, even when the sheet types have been switched, it is possible to continue execution of printing operation without stopping the printing operation just by switching the sheet supply trays, enabling efficient execution of print jobs.
In the above-described image forming system, however, in a case where a sheet shortage, or the like, occurs during execution of a print job of printing sheets of a plurality of sheet types, printing operation has to be stopped until user operation such as sheet refilling is finished. This would consequently cause deterioration of system productivity. Moreover, in execution of the print job of printing sheets of the plurality of sheet types, determining optimum operation for replacing a sheet in a tray is not easy. This also causes deterioration of productivity of the system.
To cope with this, techniques are proposed for replacing the sheet in the tray efficiently in order to avoid deterioration of productivity of the system. JP 2013-20490 A, for example, discloses an imaging forming system used in an image forming apparatus including a plurality of trays. Specifically, the image forming system, when executing a plurality of print jobs using one or a plurality of types of sheets, determines an optimum tray usage schedule based on an evaluation value onto which the number of times of sheet replacement has been reflected from a plurality of combinations of the trays and the sheet types. According to the image forming system described in JP 2013-20490 A, the number of times of sheet replacement during a print job can be reduced.
Unfortunately, the image forming system described in JP 2013-20490 A has a following disadvantage. That is, there may be, during execution of a print job, a case of occurrence of a time zone in which a user/operator is absent due to other operation, or the like, and the user, or the like, is not available for executing operation related to the image forming system. When execution of a print job using a plurality of sheet types brings about overlapping of timing of user operation such as sheet refilling to an inserter, with the user/operator unavailable timing, printing operation might stop and lead to deterioration of system productivity.